(a) Field of the Invention
The present invention relates to a superhydrophilic surface body, a fabricating method thereof, and a filter for oil and water separation, which includes a superhydrophilic surface.
(b) Description of the Related Art
The wettability refers to the degree of wetting of a solid surface by water, and is expressed as a contact angle of any liquid with respect to a base material when the liquid is brought into contact with the base material. Superhydrophilicity exhibits a property that a water drop rapidly diffuses while the contact angle between water and a base material is 10° or less. A superhydrophilic surface may be fabricated by a method of forming a fine unevenness structure on the surface of a base material or coating the surface of the base material with a material having a high surface energy.
As a method of making a fine unevenness structure, a micro-electromechanical system (MEMS) process, an etching process using a chemical solution, an anodic oxidation process, and the like are disclosed. However, these methods have drawbacks in that materials to which these methods can be applied are limited and it is difficult to apply these methods to a base material having a complicated shape and a large size. As a material having a high surface energy, titanium oxide (TiO2) which is a photocatalyst and is biologically and chemically stable may be considered, but a TiO2 coating layer has a drawback in that the binding force with a base material is weak.
Meanwhile, the wettability of the surface may be utilized in order to separate water and oil from a mixed solution of water and oil. For example, when the surface of a filter is made to be superhydrophilic, water easily passes through the filter, whereas oil is repelled by water absorbed on the surface of the filter, and as a result fails to pass through the filter. The oil and water separation method has merits in that the method is eco-friendly because the structure of the method is simple and consumable products or external energy sources are not required, and the oil recovery rate is high.
However, filters for oil and water separation in the related art, which have a superhydrophilic surface, act under low pressure, and as a result, the throughput thereof is limited, and oil passes through the filter under high pressure regardless of the wettability of the surface, and as a result, the separation efficiency is reduced. Further, commercially widely used polymer filters are usually fabricated by using hydrophobic materials, and since the hydrophobic materials have poor adhesion characteristics with respect to a coating material and it is difficult to modify the surface of the hydrophobic material, it is difficult to fabricate the surface of the hydrophobic material so as to maintain superhydrophilicity.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.